A. Field of the Invention
This invention relates to the fields of telecommunications and wireless Internet Protocol (IP) network routing. More particularly, the invention relates to a process by which a mobile communications device, for example, a laptop computer equipped with a cellular telephone modem, is located and communication between the device and a terminal on an IP network is initiated.
B. Description of Related Art
Wireless communications networks offer much flexibility to the user, in that they allow users of portable communications devices, such as personal digital assistants, laptop computers, telephones, and other appliances to get connected to the public switched telephone network from any location within the region served by the wireless network. Connolly et al., U.S. Pat. No. 5,325,419, discloses a personal communication system by which a user uses an RF link to a communicate with an intelligent base station. The intelligent base stations provide radio access along with an Integrated Services Digital Network (ISDN) interface to the public switched telephone network. The PSTN aspect of the system has three components: a personal communications switching center, where telephone central office switches have certain characteristics, a signaling transfer point, and a service control point where an intelligent data base exists maintaining certain user features and records.
The patent application of Yingchun Xu, et al., Ser. No. 08/887,313, assigned to the assignee of the present invention and which is fully incorporated by reference herein, describes a system by which a wireless communications device such as laptop computer may access a packet-switched (e.g., IP) data network such as a corporate backbone network or the Internet. In the Xu et al. system, a frame relay line connected to the wireless network couples the remote wireless user to the packet-switched network via an all-digital network access server. This type of network access server may be configured as an InterWorking Unit (IWU) and the two terms are occasionally used interchangeably herein. The network access server provides an interface to the frame relay line and wireless network and an interface (including router functionality) to the packet switched network. The Xu et al. application further discloses certain accounting and routing techniques that permit the network access to authorized users, while at the same time providing convenient authorization and accounting techniques to be performed by the entity operating the network access server. Network access servers suitable for use as a platform for an IWU are, per se, known in the art and commercially available from companies such as 3Com Corporation. They are also described in the patent literature. See, e.g., the patent awarded to Dale M. Walsh et al., U.S. Pat. No. 5,528,595, incorporated by reference herein.
In the prior art, the mobile device typically must dial into the IP network through a network access server in order to gain access to the IP network and communicate with a terminal on the network. If a terminal on the network were to attempt to initiate communication with the mobile terminal on its own, the terminal on the network and/or other communications elements in the IP network or wireless network would have to know several things: where the mobile terminal is located, whether it was within range of the wireless network, whether it was ready to receive the data (i.e., booted up), and possibly still other pieces of information, such as the information uniquely identifying the device in the wireless network such as its International Mobile Subscriber Identity (IMSI) number and/or its Electronic Serial Number (ESN). Obviously, this circumstance makes it quite cumbersome, if not impossible, heretofore, for a terminal on the IP network to initiate communication with the wireless device. For example, if a home agent for the mobile device receives an incoming IP packet for the device but does not have a record of where the device is located (e.g., a mobility binding record indicating where to send the packets received from the terminal), it would simply drop the packets.
The present invention attempts to overcome these problems and provide a simple, efficient and automatic way of permitting the terminal on the IP network to initiate communication with the mobile wireless communications device. More specifically, the invention uses the paging ability of the wireless network to locate the wireless mobile communications device whenever a terminal on the IP network attempts to send a packet whose IP destination address matches that of the mobile device. Once the mobile device has been paged the mobile node device automatically becomes connected to the IP network and is able to communicate with the remote terminal.